﻿using System;
using System.Text.RegularExpressions;
using System.Net.FtpClient;
using System.Globalization;

namespace Examples {
    /// <summary>
    /// This is an example a FTP file listing parser. This code in the example
    /// is currently used to parse UNIX style long listings and serves as an
    /// example for adding your own parser.
    /// </summary>
    class CustomParser {
        /// <summary>
        /// Adds a custom file listing parser
        /// </summary>
        public static void AddCustomParser() {
            FtpListItem.AddParser(new FtpListItem.Parser(ParseUnixList));
        }

        /// <summary>
        /// Parses LIST format listings
        /// </summary>
        /// <param name="buf">A line from the listing</param>
        /// <param name="capabilities">Server capabilities</param>
        /// <returns>FtpListItem if the item is able to be parsed</returns>
        static FtpListItem ParseUnixList(string buf, FtpCapability capabilities) {
            FtpListItem item = new FtpListItem();
            Match m = null;
            string regex =
                @"(?<permissions>[\w-]{10})\s+" +
                @"(?<objectcount>\d+)\s+" +
                @"(?<user>[\w\d]+)\s+" +
                @"(?<group>[\w\d]+)\s+" +
                @"(?<size>\d+)\s+" +
                @"(?<modify>\w+\s+\d+\s+\d+:\d+|\w+\s+\d+\s+\d+)\s+" +
                @"(?<name>.*)$";

            if (!(m = Regex.Match(buf, regex, RegexOptions.IgnoreCase)).Success)
                return null;

            if (m.Groups["permissions"].Value.StartsWith("d"))
                item.Type = FtpFileSystemObjectType.Directory;
            else if (m.Groups["permissions"].Value.StartsWith("-"))
                item.Type = FtpFileSystemObjectType.File;
            else
                return null;

            // if we can't determine a file name then
            // we are not considering this a successful parsing operation.
            if (m.Groups["name"].Value.Length < 1)
                return null;
            item.Name = m.Groups["name"].Value;

            if (item.Type == FtpFileSystemObjectType.Directory && (item.Name == "." || item.Name == ".."))
                return null;

            ////
            // Ignore the Modify times sent in LIST format for files
            // when the server has support for the MDTM command
            // because they will never be as accurate as what can be had 
            // by using the MDTM command. MDTM does not work on directories
            // so if a modify time was parsed from the listing we will try
            // to convert it to a DateTime object and use it for directories.
            ////
            if ((!capabilities.HasFlag(FtpCapability.MDTM) || item.Type == FtpFileSystemObjectType.Directory) && m.Groups["modify"].Value.Length > 0)
                item.Modified = m.Groups["modify"].Value.GetFtpDate(DateTimeStyles.AssumeUniversal);

            if (m.Groups["size"].Value.Length > 0) {
                long size;

                if (long.TryParse(m.Groups["size"].Value, out size))
                    item.Size = size;
            }

            if (m.Groups["permissions"].Value.Length > 0) {
                Match perms = Regex.Match(m.Groups["permissions"].Value,
                    @"[\w-]{1}(?<owner>[\w-]{3})(?<group>[\w-]{3})(?<others>[\w-]{3})",
                    RegexOptions.IgnoreCase);

                if (perms.Success) {
                    if (perms.Groups["owner"].Value.Length == 3) {
                        if (perms.Groups["owner"].Value[0] == 'r')
                            item.OwnerPermissions |= FtpPermission.Read;
                        if (perms.Groups["owner"].Value[1] == 'w')
                            item.OwnerPermissions |= FtpPermission.Write;
                        if (perms.Groups["owner"].Value[2] == 'x' || perms.Groups["owner"].Value[2] == 's')
                            item.OwnerPermissions |= FtpPermission.Execute;
                        if (perms.Groups["owner"].Value[2] == 's' || perms.Groups["owner"].Value[2] == 'S')
                            item.SpecialPermissions |= FtpSpecialPermissions.SetUserID;
                    }

                    if (perms.Groups["group"].Value.Length == 3) {
                        if (perms.Groups["group"].Value[0] == 'r')
                            item.GroupPermissions |= FtpPermission.Read;
                        if (perms.Groups["group"].Value[1] == 'w')
                            item.GroupPermissions |= FtpPermission.Write;
                        if (perms.Groups["group"].Value[2] == 'x' || perms.Groups["group"].Value[2] == 's')
                            item.GroupPermissions |= FtpPermission.Execute;
                        if (perms.Groups["group"].Value[2] == 's' || perms.Groups["group"].Value[2] == 'S')
                            item.SpecialPermissions |= FtpSpecialPermissions.SetGroupID;
                    }

                    if (perms.Groups["others"].Value.Length == 3) {
                        if (perms.Groups["others"].Value[0] == 'r')
                            item.OthersPermissions |= FtpPermission.Read;
                        if (perms.Groups["others"].Value[1] == 'w')
                            item.OthersPermissions |= FtpPermission.Write;
                        if (perms.Groups["others"].Value[2] == 'x' || perms.Groups["others"].Value[2] == 't')
                            item.OthersPermissions |= FtpPermission.Execute;
                        if (perms.Groups["others"].Value[2] == 't' || perms.Groups["others"].Value[2] == 'T')
                            item.SpecialPermissions |= FtpSpecialPermissions.Sticky;
                    }
                }
            }

            return item;
        }
    }
}
